Heavy guns such as artillery are sometimes used against foot soldiers, particularly where the target is out of range of machine gun bullets, or where there is no line of sight to the target. However, foot soldiers may be spread out over a large area and the damage caused by a conventional shell is too localized to be effective in such scenarios. One known approach for destroying foot soldiers under these conditions is to use a “cargo projectile” loaded with submunition grenades. The cargo projectile is a shell that is designed to be fired from large caliber cannons such as artilleries or tanks over the position of enemy foot soldiers. A plurality of submunition grenades are released and dispersed from the cargo projectile over a large area of ground. Such submunition grenades may be designed to explode in the air or may be designed to explode on impact.
The use of improved conventional munitions (ICMs) which can deliver a very large number of submunitions by means of an artillery or rocket carrier on a target area has increased the problem of hazardous duds that remain on the battlefield. The danger to follow-up friendly personnel has increased in recent time because of the large quantities of ICM carriers that have been deployed in each mission. Because of the large quantity of submunitions now deployed during each mission, all prior inputs have proven to still leave a prohibitive number of hazardous duds on the battlefield.
The basic requirements for submunition grenades include (i) a high degree of safety during storage and handling, both prior, during and subsequent to their being packed into cargo projectiles, (ii) reliability during deployment, i.e. that they should explode appropriately after release from the cargo projectile, and not prematurely, prior to their dispersal, (iii) the number of dangerous dud grenades that do not explode on impact should be minimized, and (iv) in certain cases, they should be prevented from explosion if they are dropped off the cargo projectile for any reason, before the projectile is fired. The minimization of dangerous duds is very important since if they are scattered over the battlefield, they would pose hazard to friendly troops and even to civilians or wildlife long after the battle. It will be appreciated that these requirements are to some extent contradictory, and the development of safe but highly explosive ordnance is not trivial.
Each submunition grenade includes a casing that disintegrates into lethal shrapnel when the submunition grenade explodes, a warhead for exploding the casing, and a fuze for detonating the warhead. To achieve the required safety levels in handling and storage, but reliability of the submunition grenade after releasing, the fuzes thereof are sophisticated devices that generally include chemical, mechanical and occasionally electrical subcomponents.
Typically the fuze of an impact type of submunition grenade includes a chemical detonator and a firing pin that triggers the detonator on impact. To allow the grenades and the cargo projectiles that contain such grenades to be handled safely, various safety mechanisms have been devised. Typically, in addition to the armed position in which is the grenade's fuze aligned to trigger the detonator, the firing pin of the submunition grenade also has a safe position, and when the firing pin is in this safe position, the submunition grenade can be handled and even dropped without fear of it detonating. However, once the firing pin is moved to the armed position however, an impact or similar jolt will cause the pin to detonate the detonator, igniting the warhead and thereby causing the submunition grenade to explode.
A known safety mechanism for submunition grenades is a slider assembly that keeps the detonator in a safe position away from the firing pin, preventing inadvertent detonation. After being detached from the cargo projectile, the centrifugal forces on the submunition grenade cause the slider assembly to slide into the armed position, aligning the detonator with the firing pin. Once aligned, a catch locks the slider in place such that upon appropriate impact, such as an impact with a hard surface, the firing pin is driven forward to strike the appropriately aligned detonator, detonating it, thereby igniting the warhead of the submunition grenade.
Like all mechanical systems, such slider assemblies are not fail-safe. Occasionally, they do not retract, or do not retract fully. This can happen, for example, when the striker assembly is locked for some reason.
One disadvantage of the prior art submunition fuzes described above, is that where the submunition grenade impacts with an inappropriate surface, such as a soft surface, or where the angle of impact is wrong, such that the firing pin is not induced to strike the detonator, the grenade is not detonated. Consequently, there is a risk of armed submunition grenades launched at the enemy but not detonated on impact being left scattered over the battlefield. Wherever a submunition grenade does not detonate it is considered as being a “dud”. Armed dud submunition grenades remain dangerous, and pose a risk to friendly troops and even to civilians long after the battle.
Submunition grenade fuzes are known that have a locked safe position for the firing pin that is designed to prevent the firing pin from being moved to the armed position inadvertently. When the grenades are packed into a cargo projectile carrier, the firing pin of each grenade fuze is unlocked, but it remains in its safe position until the fuze is armed. This only happens after the submunition grenade is ejected from the cargo projectile. In a submunition grenade of this type, one end of the shaft of the firing pin protrudes outside the fuze housing, and to the protruding end a drag producing means is fitted. The cargo projectile warhead spins in flight due to rifling of the barrel of the gun from which it is launched. When the grenades are ejected from the cargo projectile, the drag producing means, typically a nylon ribbon is activated. This drag producing means acts in an inertial manner, countering the spin of the submunition grenade around its longitudinal axis, and displaces the firing pin assembly, causing it to assume a striking position. In his manner, the fuze is armed automatically, but only after ejection. On impact, the firing pin assembly is driven into the grenade with a force that causes the detonation of the fuze detonator and explosion of the warhead thereby.
In certain scenarios, the submunitions may be accidentally ejected from the assembled round due to nearby explosions, fire or other similar events. Following such accidents, the submunitions is usually armed, posing a very serious safety problem.
Thus, despite the many safety features included in submunition grenades (see for example U.S. Pat. No. 5,387,257 by M. Tari, et al., U.S. Pat. Nos. 6,142,080 and 6,145,439 by R. T. Ziemba, U.S. Pat. No. 6,244,184 by O. Tadmor, and U.S. Pat. No. 7,168,367 by A. Levy, et al.), there is still a risk of armed submunition grenades being dispersed over the battlefield but not detonated.
A need therefore exists for power source and safety mechanisms for secondary electrically operated self-destruct fuzes for submunitions that function in the event a mechanical or other primary fuze mode fails to function.
A need also exists for power sources that are not based on chemical batteries, including reserve batteries, that are cost effective and easy to mass produce and that provide for very long shelf life of sometimes over 20 years.
Furthermore, a need exists for power sources that are simple in design and operation, thereby are easy to manufacture and perform quality control to ensure reliability and long shelf life.
Furthermore, a need exists for power sources with essentially zero stored power, whether chemical or mechanical or electrical or in any other forms before the projectile firing while the submunitions and/or the cargo projectile packed with the submunitions are in storage.
Furthermore, a need exists for power sources and safety mechanisms that differentiate accidental acceleration profiles from those that are encountered during projectile firing and can also be during submunitions expulsion from the cargo projectile.
The present invention provides a method for the development of such power sources with integrated mechanisms to provide for the aforementioned safety requirements. In addition, a number of exemplary embodiments for such power sources with integrated safety mechanisms are disclosed.
The present invention relates generally to power source and safety mechanisms for munitions. In particular, it relates to secondary electrically operated self-destruct fuze for submunitions that function in the event a mechanical or other primary fuze mode fails to function.
An objective of the present invention is to significantly reduce the number of hazardous duds in the battlefield, thereby improving battlefield safety conditions for friendly troops passing through a former targeted area and for civilians after the battle.
A further objective of the present invention is to improve the life/cost saving in explosive ordnance disposal procedures.
A further objective of the present invention is to significantly reduce the cost of power sources in electrically operated fuzing in general and in self-destruct secondary fuzes in particular.
A further objective of the present invention is to reduce the complexity of the design, manufacture and testing and quality control of power sources in electrically operated fuzing in general and in self-destruct secondary fuzes in particular, thereby providing power sources that are more reliable.
A further objective of the present invention is to provide power sources that are less susceptible to environmental conditions such as corrosion, thereby could satisfy very long shelf life of sometimes over 20 years.
A further objective of the present invention is to provide a power source for self-destruct fuzes that have essentially zero electrical and/or mechanical and/or chemical and/or other types of stored energy prior to the projectile launch and that energy, mechanical and/or electrical is generated at least partially due to the firing acceleration.
A further objective of the present invention is to provide power sources with primary safety mechanisms that would allow them to initiate power generation essentially only if the projectile experiences an acceleration profile that is expected during the firing or a specified acceleration profile.
It is yet another objective of the present invention to provide power sources with secondary safety mechanisms for use in self-destruct fuzes for submunitions that would essentially prevent power generation only if the projectile experiences an acceleration profile that is expected during the firing (or a specified acceleration profile) and then experiences an acceleration profile due to the detonation of the submunitions expulsion charges.
Another objective of the present invention is to remove a source of (duds) booby trap application by an enemy.